computing Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, hardware and softw ...

system generation or sysgen is the process of creating a particular unique instance of an

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

by combining user-specified options and parameters with manufacturer-supplied general-purpose program code to produce an operating system tailored for a particular hardware and software environment. The term is primarily used when referencing older

mainframe A mainframe computer, informally called a mainframe or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterpris ...

and

minicomputer A minicomputer, or colloquially mini, is a type of general-purpose computer mostly developed from the mid-1960s, built significantly smaller and sold at a much lower price than mainframe computers . By 21st century-standards however, a mini is ...

operating systems. Some other programs have similar processes, although not usually called "sysgen." For example,

IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...

's Customer Information Control System (CICS) was installed through a process called ''CICSGEN''.

Rationale

A large general-purpose program such as an operating system has to provide support for all variations of

Central processing unit A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary Processor (computing), processor in a given computer. Its electronic circuitry executes Instruction (computing), instructions ...

(CPU) that it might be run on, for all supported

main memory Computer data storage or digital data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processin ...

sizes, and for all possible configurations of

input/output In computing, input/output (I/O, i/o, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, such as another computer system, peripherals, or a human operator. Inputs a ...

(I/O) equipment. No one installation requires all this support, so system generation provides a process for selecting the options and features actually required on any one system. Sysgen produces a system that is most efficient in terms of CPU time, main memory requirements, I/O activity, and/or disk space. Often these parameters can be traded off, for example to generate a system that requires less memory at the expense of increased disk I/O operations.

Examples

* The

Burroughs large systems The Burroughs Large Systems Group produced a family of large 48-bit computing, 48-bit mainframe computer, mainframes using stack machine instruction sets with dense Syllable (computing), syllables.E.g., 12-bit syllables for B5000, 8-bit syllables f ...

Master Control Programs (MCP) were written in high-level

ALGOL ALGOL (; short for "Algorithmic Language") is a family of imperative computer programming languages originally developed in 1958. ALGOL heavily influenced many other languages and was the standard method for algorithm description used by the ...

-like languages ESPOL or NEWP. The MCP is tailored by coding $OMIT conditional-compilation pragmas, which conditionally bypass compilation of specified pieces of code. * IBM

System/360 The IBM System/360 (S/360) is a family of mainframe computer systems announced by IBM on April 7, 1964, and delivered between 1965 and 1978. System/360 was the first family of computers designed to cover both commercial and scientific applicati ...

Disk Operating System (DOS) was written in assembler. The systems programmer performing the sysgen codes assembler macros specifying the desired options and assembles the supervisor. *

OS/360 OS/360, officially known as IBM System/360 Operating System, is a discontinued batch processing operating system developed by IBM for their then-new System/360 mainframe computer, announced in 1964; it was influenced by the earlier IBSYS/IBJOB a ...

had a two-step procedure called ''Stage I'' and ''Stage II''. In Stage I the programmer specified the options for the system in a set of macros and assembled them. The output of Stage I was a job stream which contained the job control to perform all the necessary assemblies, link edits, and to create the required system libraries and copy the necessary modules into them. * RSX-11M had a three-phase SYSGEN that was required to add new hardware to the base executive.

References

{{operating-system-stub System software

Rationale

Examples

See also

References